Lubricating grease containing soaps of tall oil



- used in the earlier product.

Patented Nov. 20, 1951 LUBRICATIN G GREASE CONTAINING SOAPS OF TALL OILArnold J. Morway, Rahway, and John J. Kolfenbach, Somerville, N. J.,assignors to Standard Oil Development Company, a corporation of DelawareNo Drawing. Application April 9, 1949, Serial No. 86,586

7 Claims.

The present invention relates to lubricating greases and particularly tolubricating greases which contain as thickening agents mixtures of highand low molecular weight metal salts of organic acids.

In an application Serial No. 57,565 filed October 30, 1948, by Morwayand Young, now Patent No. 2,516,136, of which one of the presentinventors was a co-inventor, there is disclosed a new type oflubricating grease composition which is particularly suitable forhightemperature lubrication. The grease in question combines salts ofheterocyclic acids with conventional soaps, for example the soaps ofhydrogenated fish oil acids having an average chain length in the fattyacid radical of about 18 carbon atoms, or, more broadly, 14 to 22 carbonatoms. The patent points out that furoic acid may be added to the fattyacids in the presence of mineral oil and neutralized to form the saltand the soap and these are simultaneously dispersed in the mineral'oilto form lubricating grease. The saponifying agent, for example sodiumhydroxide, forms a sodium furoate along with the usual sodium soap. Thepatent points out that other cyclic acids of comparable molecular weightand structure may be used in lieu of furoic acid. For example,derivatives of thiophene may be used and the salts of other lowmolecular weight acids having similar properties are contemplated.

The present invention is based upon the discovery that greases of thegeneral type set forth in said patent may be produced very economicallyby substituting tall oil for the fatty oils or acids Certain unexpectedadvantages accrued from such use and constitute a major aspect of thepresent invention, as will be more fully pointed out hereinafter.

In another copending application Serial No. 60,615 filed November 17,1948, by the present applicants, now Patent No. 2,518,137, a process forpreparing high temperature lubricating greases is described whereinfuroic acid salts and analogous materials are produced in situ by usingan aldehyde which is converted first into an acid and then. into a saltby the well-known Cannizzaro reaction. In the present case, lubricatinggreases may be prepared by the same process, the essential differencebeing that tall oil is used in lieu of conventional fatty acids, thesalts of low molecular weight being produced by the Cannizzaro reactionwhich results when aldehydes such as furfural or thiophene aldehyde,benzaldehyde, and the like, are treated with a strong base such assodium hydroxide.

In recent years, supplies of fats and fatty acids have at times beenscarce and in some cases almost unobtainable. Hydrogenated fats andfatty materials have been used to some extent to pro- .vide saturated orsubstantially saturated materials which are preferred for grease making,but in many instances these materials have not been available or, ifavailable, have been prohibitive in price. According to the presentinvention, tall oil which is a relatively cheap by-product of the woodpulp industry may be used to form materials which replace conventionalfats and fatty acids totally or in part in forming the soap ingredientof lubricating greases of the type under discussion. Thus, lubricatinggreases containing the soaps of tall oil, particularly the alkali metalsoaps and especially the sodium soaps, are particularly effective incombination with the corresponding salts of the lower cyclic acids, e.g. those containing 4 to about 7 carbon atoms such as furoic acid,thiophene carboxylic acid, benzoic acid, salicylic acid, and the like.To some extent tall oil soaps may also be combined with other lowmolecular weight salts than the furoates, e. g. with acrylates,acetates, and other lower aliphatic salts.

In the preparation of greases of this character, the cyclic or other lowmolecular weight acid may be added directly to the composition if theCannizzaro reaction is not desirable, or if the aldehydes are notavailable. In many cases, the use of the corresponding aldehyde,particularly furfural, is justiiied economically as a source of the lowmolecular weight acid which forms the salt component. because of theavailability and cheapness of this material. When the neutral orsubstantially neutral salts and soaps are derived from relativelyinexpensive aldehyde and the relatively inexpensive tall oil, either asthe principal or as the total thickening ingredients, the resultinggrease product is quite inexpensive and has very useful properties. Talloil acids or tall oil saponified with sodium hydroxide and dispersed inmineral oil gives greases of low dropping point, undesirably fibrous,and poor oxidation and structural stability.

The addition of the cyclic acid salt in combination with soaps of talloil acids, improves the oxidation stability far beyond that obtainedwith tall oil soap alone in greases. In fact the furoic acid saltappears to act as a synergist for the commonly used oxidation inhibitorphenyl alpha naphthylamine. High dropping point, smooth short fiberstructure and excellent structural stability are also obtained.

The mere addition of the sodium salt of Iuroio acid in combination witheither a Simple sodium linoleate or a. simple sodium oleate, bothcomponents of tall oil acids, do not give greases of good structuralstability. Moreover, in the past, the rosin acids which are an importantingredient in the conventional tall oil of commerce were believed to beobjectionable. However, when tall oil is used in combination with thefuroic acid salts it appears that small quantities of rosin acid soapswhich result are beneficial. However, no atttempt is made here toexplain the behavior mechanism in the performance of such greases.

Furfural is a widely available and inexpensive material, widely used asa selective solvent in industry. Tall oil is a by-product of the paperpulp industry as noted above. Another by-product obtained in thesulfate-paper process is sulfate turpentine, a product objectionable foruse in lubricants because of its odor and color. Trimble, in U. S.Patent 2,310,046, describes the refining of sulfate turpentinesimultaneously with crude tall oil by using furfural. Separation of theturpentine and tall oil is accomplished by distillation under reducedpressure. Any furfural remaining in the tall oil, either as the monomeror polymer, may be determined and this residue may be left in therefined tall oil. Upon saponification of the tall oil the salts offuroic acid are also produced. Sufficient furfural may be added ifneeded, to form the required proportions of low molecular weight saltsrequired for the grease.

Any commercial type of tall oil acids may be employed in carrying outthis invention. However, the acids obtained by at least one completedistillation of the crude tall oil are preferred.

The invention will be better understood by reference to the followingspecific examples:

EXAMPLE I Charging formulation Per Cent Free Alkalinity-0.22% as NaOH.

In the manufacture of this grease, the furfural (1 part by weight) and aportion of the mineral oil (3 parts) were charged to a grease kettle andstirring initiated. A cold aqueous 33 solution of NaOH (shown in theabove formulae as part of the Cannizzaro reactions) was next added.After the reaction is completed as shown by subsidence of thetemperature of reaction, the tall oil (having an acid number of 183.2and Sap. No. of 185.2) was added and neutralized with the balance of theNaOH as a 40% aqueous solution.

The temperature was next raised by external heating to 400 F. whileadding the balance of the mineral oil in small portions. At this tem-'peraturethe phenyl alpha naphthylamine, used as an antioxidant, wasadded and the grease was drawn into pans for cooling. It could be workeddown in the kettle while cooling if desired. The cold grease was thenhomogenized by working in the grease kettle to a smooth, uniformproduct, after which it was filtered and packaged. This grease containedabout 6% sodium furoate and about soda soap of tall oil.

' '4 The following properties were found upon inspection:

Worked penetration 180 mm./10. Structure stability, as measured by apenetration of 268 mm./10 after working 100,000 strokes with a fine holeworker plate Excellent. Dropping point, F Above 500. 50 hour separationtest, 60 mesh cone at 210 F. (per cent separation) None. Wheel bearingtest, 6 hours at 220 F Pass. Oxidation test, Norma Hoffman bomb 102 hrs.to 5 p. s. i.

drop in pressure. 1 No slumping, no oil separation, slight hardening.

position of poor structural stability resulted. The composition lost itssolid consistency and broke down after working in a standard greaseworker for 50,000 strokes to a semifluid mass which could be poured.

EXAMPLE III The same formula as shown in Example I was used and the samemethod of manufacture, except that the tall oil employed contained morerosin soap, having the following chemical and physical properties:

Acid value 175.0 Composition (approx.) fatty acids as oleic and linoleicacids per cent 30 Rosis acids do 70 In this example the tall oil wasmixed with equal portions of hydrogenated fish oil acids (HydIOfOl Acids54) Properties of Grease Free alkalinity 0.32% as NaOH. Workedpenetration mm./ 10 210. Structural stability Excellent. (Penetration af t e r 100,000

s t r o k e s fine hole worker plate) 248. Dropping point F 500+.

Separation (50 hours at 210% None. Wheel bearing test 6 hours at Pass.

220F hours 5 Norma Hoffman oxidation p. s. 1. drop in (210 F.) ()2pressure.

1 Same as in Example I.

The proportions of the various ingredients may be varied over widelimits provided that the ratio between the low molecular weight salt andthe soap of tall oil is maintained between predetermined limits. A verysatisfactory modified soap may be made by using substantially equalparts of saturated fatty acids, such as C12 to C22 hydrogenated fish oilacids, with tall oil. As pointed out in the Morway and Young, Patent No.2,516,136, referred to above, 1 to 3 molar parts of soap should be usedwith about 1 to 2 molar parts of salt. When employing the Can nizzaroreaction as disclosed in Patent No. 2,516,- 137, mentioned above, 2parts of furfural can be used with 3 parts combined fatty acid and/ortall oil. Since tall oil consists essentially of a mixture of rosinacids and oleic acid the soaps which result are partly rosin soaps andpartly oleates. The total proportions of such soaps, however, may bewithin the limits of about 5 to 20% by weight, based on the totalcomposition, the salt of low molecular weight acid being in proportionsof about 2 to generally speaking. Proportions of 3 to 7% salts of cyclicacid (such as furoic acid) combined with 8 to of the soaps of tall oilacids are specifically preferred, the remainder of the composition beinglubricating oil.

The grade of mineral oil may be varied over wide limits as is well-knownin the art. It may comprise from about 60 to 93% of the totalcomposition and should be of appropriate lubricating grade for the'lubrication requirements. Its viscosity may be from about S. U. S. toabout 150 S. U. S. at 210 F. or about 50 to 1,000 S. U. S. at 100 F.Either naphthenic or paraffinic oils, or mixtures thereof, may be used.

Conventional additives such as antioxidants, oiliness agents, corrosioninhibitors, extreme pressure compounds, and the like, may be used inusual proportions, as will be understood by those skilled in the art.While mineral base oils are preferred, they may be supplemented by orcompounded with synthetic oils such as the oily esters of dibasic acids,polyglycols, and the like. The term lubricating oil as used in thefollowing claims will be understood to apply to any of such oils or acombination thereof where not otherwise specified. Where the Cannizzaroreaction is not employed, the salts and soaps may be formed separatelyand combined in the oil. or they may be formed in situ as may bedesired. If the Cannizzaro reaction is employed, both the soap and thesalt of the cyclic acid should be prepared in situ and preferablysimultaneously.

What is claimed is:

l. A lubricating grease composition consisting essentially oflubricating oil thickened to a grease consistency with a combination of5 to 20% by weight based on the total composition, of the sodium soap oftall oil combined with 2 to 10% of the sodium salt of a low molecularweight cyclic carboxylic acid containing 4 to about '1 carbon atoms.

2. Composition as in claim 1 wherein the cyclic acid is furoic acid.

3. Composition as in claim 1 wherein the cyclic acid is thiophenecarboxylic acid.

1 4. Composition as in claim 1 wherein the salt of low molecular weightacid is a benzoa'te.

5. A lubricating grease composition consisting essentially of to 93% byWeight of mineral base lubricating oil, 5 to 20% of a soda soap of talloil and 2 to 10% of sodium furoate.

6. A lubricating grease composition consisting essentially of minerallubricating oil having a viscosity between 35 and S. U. S. at 210 F.,thickened to a grease consistency with a combination of about 15% byweight, based on the total composition, of the soda soap of highmolecular weight organic material of the class consisting of highersaturated fatty acids and their esters and tall oil and comprising asubstantial proportion of tall oil and about 6% of sodium furoate.

7. Composition as in claim 6 wherein the nonmetal radical of the highmolecular weight soap is composed of substantially equal parts ofsubstantially saturated fatty acids of 12 to 22 carbon atoms and talloil.

ARNOLD J. MORWAY. JOHN J. KOLF'ENBACH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,182,137 Ricketts Dec. 5, 19392,444,720 Bell July 6, 1948 2,514,286 Morway July 4, 1950 2,516,136Morway et a1. July 25, 1950 2,516,137 Morway et ,1 July 25, 1950

6. A LUBRICATING GREASE COMPOSITION CONSISTING ESSENTIALLY OF MINERALLUBRICATING OIL HAVING A VISCOSITY BETWEEN 35 AND 150 S. U. S. AT 210*F., THICKENED TO A GREASE CONSISTENCY WITH A COMBINATION OF ABOUT 15% BYWEIGHT, BASED ON THE TOTAL COMPOSITION, OF THE SODA SOAP OF HIGHMOLECULAR WEIGHT ORGANIC MATERIAL OF THE CLASS CONSISTING OF HIGHERSATURATED FATTY ACIDS AND THEIR ESTERS AND TALL OIL AND COMPRISING ASUBSTANTIAL PROPORTION OF TALL OIL AND ABOUT 6% OF SODIUM FUROATE.